1. Field of the Invention
The present invention relates generally to the erection of sectional towers, and more particularly to method and apparatus for erecting a portable sectional tower of the type used in communication systems.
2. Description of the Prior Art
There are a number of important industrial and military field operations in which it is necessary to transport a portable communications tower to a remote field location, erect the tower, establish a temporary communications center during a temporary operation, and then move to a new location. Three important considerations for such operations are safety, economy, and mobility. In regard to safety considerations, one of the most hazardous aspects of tower erection is the requirement for climbing the tower to attach communications equipment. Safety can be greatly improved if the attachment of equipment such as guy wires, antennas, coax cables and antenna assemblies can be done at or near ground level so that tower climbing is eliminated. This is especially important when operating in remote field locations in cold and windy weather. Among the economic considerations are the auxiliary equipment and personnel required to carry out the tower erection. When operating in remote field locations, it would be desirable to minimize the number of attendants and operators necessary for carrying out the erection, and furthermore to reduce the number of steps and to minimize the auxiliary equipment required. Such arrangements are also desirable in that it would eliminate the requirement for the hiring and support of a large number of tower erection personnel and also would eliminate the costly and time consuming training. Finally, mobility is an important consideration for certain field operations in which it is necessary to transport a communications tower to a remote location, erect the tower, set up and operate a communications center during a temporary operation, and then disassemble the tower and transport it to a new field location.
A great number of accidents involving the collapse of the tower have occurred because of improper guy wire support. Because of the wind loading effect, it is important that a communication tower be provided with guy wire support during erection as well as after it is fully extended. Therefore, the tower erection procedure has proven to be difficult and dangerous unless a large number of personnel are available to tighten and secure the guy wires simultaneously and uniformly as the tower is erected. Such a requirement is obviously incompatible with conventional portable towers, especially when operating in remote field locations. The safety and economy considerations are equally important when the portable tower is disassembled.
Therefore, it is an important object of the present invention to provide apparatus for erecting a portable sectional tower which includes means for automatically and simultaneously applying a tension load to the guy wires as the tower is erected, thereby eliminating the need for a separate, manually supervised tightening operation.
It is another object of the present invention to provide portable erection apparatus in which tower sections are extended successively from the ground level up so that the attachment guy wires and antenna equipment can be carried out at near ground level whereby tower climbing is practically eliminated.
It is a further object of the present invention to provide a self-contained mobile carriage assembly on which sectional tower members may be transported to a remote location and from which the tower sections may be safely erected by a minimum number of personnel.